Use of JYNNEOS (Smallpox and Monkeypox Vaccine, Live, Nonreplicating) for Preexposure Vaccination of Persons at Risk for Occupational Exposure to Orthopoxviruses: Recommendations of the Advisory Committee on Immunization Practices — United States, 2022
Authors: Agam K. Rao, Brett W. Petersen, Florence Whitehill, Jafar H. Razeq, Stuart N. Isaacs, Michael J. Merchlinsky, Doug Campos-Outcalt, Rebecca L. Morgan, Inger Damon, Pablo J. Sánchez, Beth P. Bell
Journal: MMWR Morbidity and Mortality Weekly Report (2022)

RecommendationsVaccine product ACAM2000 JYNNEOS Who should receive the vaccine?Persons at risk for occupational exposure to orthopoxviruses* Who should be offered the vaccine?Persons who administer ACAM2000 or care for patients with infection with replication-competent viruses Populations for whom booster vaccination is recommended at specific intervals Persons who are at ongoing risk † for occupational exposure to orthopoxviruses Booster frequency § Persons working with more virulent orthopoxviruses (e.g., Variola virus or Monkeypox virus) Every 3 years Every 2 years Persons working with less virulent orthopoxviruses (e.g., Vaccinia virus or Cowpox virus) At least every 10 years * Research laboratory personnel working with orthopoxviruses, clinical laboratory personnel performing diagnostic testing for orthopoxviruses, and orthopoxvirus and health care worker response teams designated by appropriate public health and antiterror authorities.† Ongoing risk due to occupational work performed; response personnel are not considered at "sustained risk" for orthopoxvirus infections.§ Booster doses are recommended for response personnel only once an event is identified.TABLE 2. Distinctions between ACAM2000 and JYNNEOS that might facilitate decision-making among vaccinees at risk for orthopoxvirus infections -United States, 2022 Characteristic Vaccine product ACAM2000* JYNNEOS Vaccine virus Replication-competent vaccinia virus Replication-deficient modified vaccinia Ankara "Take" following vaccination † Yes No Risk for inadvertent inoculation and autoinoculation Yes No Risk for serious adverse event Yes No significant events identified during clinical trials Risk for cardiac adverse events Myopericarditis in 5.7 per 1,000 primary vaccinees Clinical trial data limited in evaluating this outcome; however, no significant events in data abstracted from single study arms § Assessment of effectiveness FDA assessed by comparing immunologic response and take rates to Dryvax* FDA assessed by comparing immunologic response to ACAM2000 and animal studies Administration Percutaneously using a bifurcated needle by multiple puncture (scarification) technique, ¶ single dose Subcutaneously, 2 doses 28 days apartAbbreviation: FDA = Food and Drug Administration.* Both ACAM2000 and Dryvax are derived from the New York City Board of Health strain of vaccinia; ACAM2000 is a second generation smallpox vaccine derived from a clone of Dryvax, purified, and produced using modern cell culture technology.† A "take" is postvaccination lesion often used as a marker of successful vaccination after ACAM2000.§ Because JYNNEOS is a replication-deficient virus vaccine, serious adverse events are believed to be fewer.However, the mechanism of myopericarditis in persons who receive ACAM2000 is poorly understood; for this reason, it is unknown whether persons who receive JYNNEOS might experience myopericarditis.